Earnings per share of QTS Realty Trust, Inc. (Computation of Basic and Diluted Net Income per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings per Share [Abstract]
Net income (loss)	$ (6,433)	$ 4,608	$ (6,685)	$ 10,176
Loss (Income) attributable to noncontrolling interests	1,002	(568)	1,031	(1,259)
Preferred stock dividends	(2,248)		(2,576)
Earnings attributable to participating securities	(227)	356	(485)	814
Net income (loss) available to common stockholders after allocation of participating securities	$ (7,906)	$ 4,396	$ (8,715)	$ 9,731
Weighted average shares outstanding-basic	50,452	47,666	50,366	47,562
Effect of Class A and Class RS partnership units		6,783		6,783
Effect of Class O units and options to purchase Class A common stock and restricted Class A common stock on an "as if" converted basis		1,009		991
Weighted average shares outstanding-diluted	50,452	55,458	50,366	55,336
Basic net income (loss) per share	$ (0.16)	$ 0.08	$ (0.17)	$ 0.18
Diluted net income (loss) per share	$ (0.16)	$ 0.08	$ (0.17)	$ 0.17